1. Technical Field
The present invention is related to insulation of a heating device, and more particularly to a multi-layered thermal insulation structure.
2. Description of Related Art
Conventional heating devices include a chamber which is assembled with a heat source therein. However, heat generated by the heat source would be dissipated to the outside due to heat conduction from wall surface of the chamber, which makes heat dissipation difficult to be avoided. If a user accidentally touches an exterior surface of the chamber, it is possible that the user might get burned. In order to reduce heat dissipation, an improved heating device which further includes a housing disposed outside of the chamber is provided. A gap is provided between the housing and the chamber to isolate heat conducted from the chamber so as to lower a temperature on the exterior surface of the chamber.
However, in addition to heat conduction, the heat transferring path also includes heat convection and heat radiation. Even if the aforementioned heating device could isolate heat conduction dissipated from the chamber, it is possible that the heat of the chamber would be transferred to the outside through heat convection and heat radiation. Hence, heat dissipation cannot effectively be eliminated for the conventional heating devices and there is still a need to provide an improvement on reducing heat dissipation of a heating device.